1. Field of the Invention
The present invention relates to an improved system and method for accurately measuring the distance between two objects using location defining data from global position indicating satellites. The invention is especially useful for accurately measuring, electronically, the distance and the direction between two spaced objects, such as the distance and direction between the hole or pin on a green of a fairway on a golf course and a golf cart located along the fairway of the golf course, or the distance and direction between the hole or pin on a green of a fairway on a golf course and a golf ball on the fairway, or an object or hazard on the golf course and a golf ball on the fairway of the golf course, or the distance and direction between the club house of a golf course and a golf cart on the golf course.
2. Prior Art
For the sake of clarity, the term xe2x80x9cholexe2x80x9d when used hereinafter shall refer to a combination of a teeing ground or tee, a fairway and a putting green associated with the fairway, on a golf course. It is well known in the field of golf, that a normal golf course consists of eighteen (18) holes; that each hole has a tee, a fairway and a green; and, that each green has a Hole or pin (hereinafter referred to as xe2x80x9cpinxe2x80x9d) into which the golf ball is holed by a golf player (hereinafter referred to as xe2x80x9cplayerxe2x80x9d). These terms and their meaning, when used in reference to the game of golf, are well known to those persons knowledgeable in golf and it is in such context that these terms are used herein.
It is usual to inform a player the distance, in yardage, between the tee and the green for each hole on the golf course. However, in most cases, the pin on the green is moved from time to time and, for convenience of the golf club, the distance between the tee and the green is measured and given from approximately the geographical center of the teeing ground to approximately the geographical center of the green. This approximation is used despite the fact that the pin on the green is very seldom located at the geographical center of the green Often, the distance between the tee and the green on the same hole, exceeds the distance a player drives the golf ball from the tee of that hole. When a player drives the golf ball short of the green, the player is left on his own to determine the distance or yardage between the golf ball on the fairway and the pin on the green of the hole being played.
The size, in area, of the green depends on the design of the golf course and, in many instances, the green may be a relatively large area. The pin, which is a hole in the green, not exceeding 108 mm in diameter and at least 100 mm in depth, (according to the 1996 Rules of Golf, published and copyrighted, 1995, by the United States Golf Association and The Royal and Ancient Golf Club of St. Andrews, Scotland) may be positioned anywhere on the green. The player, when addressing the green with his golf ball from the fairway, is most interested in knowing the distance, in yardage, as accurately as possible, between the golf ball on the fairway and the pin on the green associated with that airway.
One reason for knowing the accurate distance between the golf ball and the pin on the green or some other object on the hole being played is selection, by the player, of the club used to hit the golf ball.
It is well known that the United States government has placed a global position system, in the form of a plurality of satellites, in orbit above the earth. The global position satellites (hereinafter referred as xe2x80x9cGPSxe2x80x9d) transmit PF carriers on which frequency, time and timing signal data are modulated. The GPS transmissions (hereinafter referred to as xe2x80x9cGPS Dataxe2x80x9d) may be received by a global position signal receiver (hereinafter referred as xe2x80x9cGPS receiverxe2x80x9d). The GPS Data, received by a GPS receiver, may be translated or converted into location defining data, such as latitude and longitude coordinates, for example, that define an exact location, on earth, for the antenna of the GPS receiver receiving the GPS Data It is also known that the United States government has caused a contamination of the signals transmitted by the satellites in the global position indicating system. The contamination affects the GPS Data, causing a randomly occurring and changing inaccuracy in the location defined for the GPS receiver receiving GPS Data from satellites in the GPS system. The inaccuracy occurs and changes randomly, with time, in direction and in magnitude. Since the inaccuracy in the lotion defined for a GPS receiver receiving GPS Data is random in both occurrence and change, the location defined for a GPS receiver may be accurate or inaccurate, with respect to its actual location. Thus, although the GPS Data is correctly translated or converted, the location defined for the receiving GPS receiver may be accurate or inaccurate, the inaccuracy of the location defined being off-set from the actual, true location, in any direction, plus or minus, by as much as forty yards.
It is also known that the inaccuracy between the actual location of a GPS receiver and the location deed by the GPS Data for the GPS receiver receiving such GPS Data, can be corrected. Information relating to the global satellite position system and the inaccuracy of the location data transmitted by the satellites and how to correct such inaccuracy, is reported in a paper, xe2x80x9cThe Application of NAVSTAR Differential GPS in the Civilian Communityxe2x80x9d by Jaques Beser and Bradford W. Parkinson, published in NAVIGATION, Vol.II, 1984.
U.S. Pat. No. 5,364,093 to Huston et al, issued Nov. 15, 1994 teaches that the distance between the pin on a green and a mobile cart may be determined using GPS Data transmitted from GPS when the exact location of the pin on the green and the exact location of the mobile golf cart are each known. The Huston et al teaching provides for previously determining the exact location of the pin on the green, by independent means. The mobile cart is provided with a GPS receiver and a computer. The GPS receiver receives GPS Data which, when translated, defines an inaccurate location for the mobile cart. A differential or error signal is used to change the inaccurate location of the golf cart to an accurate location. The distance between the accurate location of the mobile golf cart and the previously determined location of the pin on the green is then calculated from two defined accurate locations.
The differential or error correction signal is generated by comparing position locating data derived from GPS Data received by a fixedly located GPS receiver with previously determined, corresponding position locating data defining the exact, correct location of the fixedly located GPS receiver. The differential or error signal is transmitted to the mobile GPS receiver on the golf cart. The exact location of the mobile cart is determined by correcting the GPS Data defining the inaccurate location of the mobile GPS receiver on the golf cart with the differential or error signal.
Huston et al, in the U.S. Pat. No. 5,364,093 , teach measuring distance between a golf cart and the pin on the green. This leaves the player to measure the distance between the golf ball on the fairway and the pin on the green because golf carts are normally not permitted to trespass on the fairway of the golf course.
The U.S. Pat. No. 5,434,789 to Fraker et al, issued Jul. 18, 1995 teaches a golf diagnostic system which uses GPS Data to provide location coordinates for plotting locations for measuring the distance of the flight of a golf ball and for measuring distance between the GPS receiver and other previously known locations on the golf course. The teaching includes using differential or error correction data signals generated by and transmitted from a fixed GPS receiver, located in a previously known and defined location, to adjust location coordinates, for accuracy. However, the teachings of both Huston et al, ""093 and Fraker et al, ""789 require the generation of differential or error signals. It is also necessary, in both teachings, to know the exact, defined location of at least one GPS receiver, in terms compatible with the GPS Data, in order to compare the GPS Data defined location with the actual location in order to generate a differential or error signal. The differential or error signal must be applied to a second GPS Data defining the location of a second GPS receiver in order to determine the correct location of the second GPS receiver. It is further necessary to know the exact, defined location, of the pin on the green of the golf course, in terms compatible with the GPS Data, in order to compare distance between the pin and the mobile receiver.
The U.S. Pat. No. 5,438,518 to Bianco et al, issued Aug. 1, 1995 teaches that a digitized map of a golf course, stored in the memory of a computer, may be used to plot the location of a mobile unit on a golf course when GPS Data is received by the mobile unit. Raw GPS Data, defining an inaccurate location for the mobile unit, is corrected using a differential or error correction signal generated using location data translated from GPS Data and the known, correspondingly defined, actual location of a fixed GPS receiver. The location defined by the GPS Data, received by the fixed GPS receiver, is compared with corresponding data defining the known, exact location of the fixed GPS receiver and a differential or error correction signal is generated. The differential or error correction signal is transmitted to and used by the mobile unit in order to adjust the location of the mobile unit for correct position plotting.
The U.S. Pat. No. 5,469,175 to Boman, issued Nov. 21, 1995 teaches a system and method for accurately measuring the distance between a golf ball on a fairway and the pin on the green. The accurate location of a mobile GPS receiver is determined by correcting the inaccurate location derived from GPS Data received by the mobile GPS receiver, using a differential correction signal. The differential signal is generated by comparing GPS Data defining, inaccurately, the location of a fixed GPS receiver, with previously known corresponding data defining the accurate location of the fixed GPS receiver. When the corrected location of the mobile GPS receiver is determined, the corrected location of the mobile GPS receiver is adjusted by the distance and direction between the golf ball on the fairway and the mobile GPS receiver. This provides an accurate location of the golf ball on the fairway. The exact location of the pin is already known and defined in corresponding location defining data and the distance between the golf ball on the fairway and the pin is calculated.
Each of the U.S. Pat. Nos. 5,364,093; 5,434,789; 5,438,518; and, 5,469,175 provides for correcting or changing an inaccurate location defined by GPS Data, with a differential or error correction data, in order to convert the inaccurate location derived from the GPS Data, to data that defines the accurate location of the GPS receiver. However, related differential or error correction data must first be determined and generated using GPS Data and the exact, previously defined location of a GPS receiver, which is defined in terms comparable with the GPS Data received from the global position satellites. After obtaining a corrected location of a mobile golf cart, distance between the golf cart and the pin is measured only when the exact location, of the pin is also previously known and defined in corresponding terns. These limitations are avoided by the present invention
U.S. Pat. No. 4,949,089 to Ruszkowski, Jr. teaches a target locator system which uses the global position satellite system to provide location coordinates for a mobile target locator. The mobile target locator measures the distance, direction and inclination between the target and the mobile target locator. Location coordinates for the target are then generated by mathematically calculating the location coordinates for the target locator, obtained from the global position satellite system, with the measured distance, direction and inclination between the target locator and the target, providing a set of location coordinates for the target. The generated target location coordinates are transmitted to the weapons delivery system, which now has the location coordinates for the target.
The present invention takes advantage of the fact that when the locations of two spaced objects are each defined in corresponding location defining terms, such as latitude and longitude or other grid coordinates, for example, the difference between the two corresponding location defining terms is the distance and direction between the two objects. This is true if correct locations are defined or incorrect locations are defined, so long as both data defining the respective locations are correspondingly accurate or both data are correspondingly inaccurate.
The present invention provides a method and/or apparatus and/or system for accurately measuring the distance and direction between two objects using the raw, contaminated GPS Data transmitted from GPS satellites in orbit and received by each of two GPS receivers. The present invention avoids determining and/or defining and/or identifying the actual, true location of either or both objects and/or GPS receivers before, during or after measuring the distance and direction between the two objects. The present invention provides for accurately measuring such distance and direction without changing or correcting the contaminated GPS Data received or changing or correcting the locations defined by the GPS Data. Accuracy in the location defined for the same site, by successive transmissions of GPS Data, changes randomly, with time. It has been found that the inaccuracy in the location defined by each of two sets of GPS Data received at substantially the same time, by two GPS receivers, is uniform and corresponding. In practicing the present invention, the difference between the GPS Data received by each of two GPS receivers at substantially the same time, is determined and from the difference between the two sets of GPS Data the distance and direction between the two GPS receivers is accurately determined.
In accordance with the invention, two (sets of) GPS Data, each in its raw, contaminated, unreliable state, received at substantially the same time by each of two GPS receivers, are used to accurately measure the distance between two objects and the direction of such distance. Two spaced GPS receivers, each of which may represent, one each, of two spaced objects, respectively, located in two undefined locations, are provided. Each GPS receiver receives GPS Data from GPS satellites, i.e., global position satellites. Each set of GPS Data, received by each respective GPS receiver, is translatable into a location defining data, which defines a location for the GPS receiver receiving the particular GPS Data. However, locations defined by GPS Data are ureliable in accuracy with respect to defining the exact location of the receiving GPS receiver. A computer or data processor is provided, programmed to receive and combine at least two sets of GPS Data, at least one set from each of the two spaced GPS receivers, for mathematically calculating the difference between the two sets of GPS Data. The difference between the two sets of GPS Data, received by two spaced GPS receivers, defines an accurate distance and direction between the two GPS receivers. In a one embodiment of the invention, both sets of GPS Data, received by the respective GPS receivers, are translated or converted into latitude and longitude coordinates, or other location defining coordinates, for example. The difference between two sets of location coordinates, each defining a different location, is mathematically calculated, deriving the distance and direction between the two locations or sites of the spaced GPS receivers receiving the respective GPS Data. The two sets of GPS Data used are in a raw, contaminated state and may be in untranslated or unconverted form or may be in contaminated but translated form. This avoids determining, identifying and/or defining the true or correct location or site of either GPS receiver; avoids the need for generating error correcting data; and, avoids the need for correcting the inaccuracy in location defined by the contaminated GPS Data, as taught in the prior art. The present invention is especially useful on a golf course for determining accurate distance and direction between two objects on the golf course, although the present invention is not limited to such use.
In accordance with one aspect of the invention, at least two GPS receivers are provided, along with a computer or data processor and at least two transmitting and/or receiving radios. One of the two GPS receivers is essentially fixed on or at the pin on the green of a hole on a golf course. The exact, defined location of the pin on the green need not be known or determined. One radio is coupled to the GPS receiver at the pin, to transmit GPS Data received by the GPS receiver at the pin. A second of the two GPS receivers is mobile or portable and may be anywhere on the golf course. The computer or data processor is associated with the mobile or portable GPS receiver. Another of the radios is coupled to the mobile GPS receiver and to the computer to receive GPS Data transmitted by the radio coupled with the GPS receiver at the pin and to apply the GPS Data, received by the GPS receiver at the pin, to the computer. The mobile GPS receiver is coupled to its associated computer to apply GPS Data received by the mobile GPS receiver to its associated computer. The GPS Data from the GPS receiver at the pin and the GPS Data from the mobile GPS receiver are traded and/or applied to the computer. The computer is programmed to mathematically calculate at least two sets of GPS Data from two spaced GPS receivers to determine the difference between the two sets of GPS Data. Since one set of GPS Data defines one location and the second set of GPS Data defines a second location then, the difference between the two sets of GPS Data defines the distance and direction of such distance between the two locations defined by the two sets of GPS Data. In the present aspect, the distance and direction determined is the distance and direction between the GPS receiver at the pin and the mobile GPS receiver on the golf course. This is the distance and direction cart-to-pin.
The mobile or portable GPS receiver may be carried across the golf course on a golf cart or in a golf bag of a player or carried by the player. When the player carries the mobile or portable GPS receiver and holds the portable GPS receiver at or over the golf ball on the fairway, the distance and direction derived by the computer is between the golf ball on the fairway and the pin. This is the distance and direction ball-to-pin. The distance and direction may be displayed visually and/or audibly.
In accordance with another aspect of the invention, at least two mobile or portable GPS receivers are provided along with at least one computer or data processor and at least two radios. Each of the GPS receivers may be mounted or carried on golf carts used on the golf course. Each of the GPS receivers may have associated therewith, a computer and each of the GPS receivers has a radio for transmitting and receiving. Each GPS receiver is for receiving GPS Data from satellites in the GPS system. One of the GPS receivers, with computer and radio is mounted or carried on a golf cart used by a Golf Course Supervisor, for example. The other GPS receiver may be mounted or carried on a golf cart used by a player on the golf course. A system, interactive between the golf cart of the Golf Course Supervisor and the player golf cart, remotely activates the GPS receiver on the player golf cart, when actuated. The GPS receiver on the player golf cart receives GPS Data which is transmitted by the on-board radio. The radio on board the golf cart of the Golf Course Supervisor receives the GPS Data transmitted from the player golf cart and applies the player GPS Data to the computer on the Golf Course Supervisor golf cart. At the same time, the GPS receiver on the Golf Course Supervisor golf cart receives GPS Data and applies the locally received GPS Data to the on-board computer. The computer mathematically calculates the difference between the two sets of GPS Data and derives therefrom the distance and direction between the Golf Course Supervisor golf cart and the player golf cart, for on-the-course golf cart tracking, leading to golf play control.
Alternatively, a GPS receiver with computer and radio may be located in the club house or pro shop of a golf course. The GPS receiver located in the club house (or pro-shop) also includes a system for selectively actuating remote GPS receivers. Using known technology, a mobile GPS receiver may be turned on remotely, in response to a coded signal transmitted by a radio, in the club house, for example. Employing a remote action system, a selected mobile GPS receiver, mounted on a player golf cart, on the golf course, is remotely activated and the GPS Data received by the selected mobile GPS receiver and the GPS Data received by the GPS receiver in the club house are transmitted and/or applied to the computer associated with the club house GPS receiver, for calculating the distance and direction between the selected player golf cart and the club house. Using a map of the golf course, the location of the selected golf cart may be determined, providing golf cart tracking and/or golf play control from the club house or pro-shop. Golf cart tracking and golf play control are discussed in U.S. Pat. No. 5,324,028, issued to Luna. For golf cart tracking, each golf cart used on the golf course may be provided with a GPS receiver and radio and each golf cart or GPS receiver may be provided with an identifying code. Golf cart tracking may be modified to provide golf player tracking, if desired.
In yet another aspect of the invention, distance and direction between a golf ball on the fairway and the pin on the green (distance ball-to-pin) is measured. When practicing this aspect of the invention, preferably a fixed GPS receiver with radio, and one or more mobile GPS receivers with computer and radio, are provided. The fixed GPS receiver is preferably located on or in the vicinity of the golf course, the exact location of each GPS receiver need not be previously determined or defined. The mobile GPS receiver may be mounted or carried on a golf cart used by a player on the golf course or by the player on the golf course. The distance and direction between the pin on the green and the fixed GPS receiver is measured, by conventional means, and is stored in the computer, for later use. The fixed GPS receiver and the mobile GPS receiver each receive respective sets of GPS Data from satellites in the global position system, preferably, at substantially the same real time. The respective sets of raw, contaminated GPS Data are applied to the computer for calculating the difference between the two sets of GPS Data, for deriving the distance and direction between the fixed GPS receiver and the mobile GPS receiver. The distance and the direction between the fixed GPS receiver and the mobile GPS receiver is a derived leg, extending from the fixed GPS receiver to the mobile GPS receiver. The distance and direction between the fixed GPS receiver and the pin, already measured and stored in the computer, is a known leg, extending from the fixed GPS receiver to the pin.
The derived leg and the known leg extend from the same point, the fixed GPS receiver. With the direction of both legs known, the angle between the legs is determined. With distance of both legs and their respective directions known, the leg connecting the extremes of the known leg and the derived leg is calculated, providing the distance and direction between the mobile GPS receiver and the pin. When the mobile GPS receiver is positioned at, near or over the golf ball on the fairway, the calculated leg is the distance and direction between the golf ball and the pin.
Distance and direction between the fixed GPS receiver and the pin, or any object or hazard on the golf course, for example, may be measured by any of several conventional means, for example, a tape measure or any mechanical, optical, electric, electronic and/or sonic distance measuring means or range finder, without the need for defining the location of either the fixed GPS receiver or the object. The term object is intended to represent a pin on a green, or a hazard on the golf course, or the club house or pro shop on the golf course, or any other object on the golf course. When practicing certain aspects of the invention, a GPS receiver may be substituted for, or represent the object, in practicing other aspects of the invention the object retains its own identity. This will be apparent to those reading this disclosure and to those practicing the invention. The distance and direction between the fixed GPS receiver and each of a plurality of objects may be measured and codified. The measurement and ID code for the particular object may be programmed and/or stored in a computer or data processor, for later retrieval and/or use. The mobile GPS receiver may represent each a plurality of GPS receivers, whether mobile or portable, transported over the golf course on golf carts or by the player, for example. A mobile GPS receiver, with an associated computer, may be mounted on a mobile unit, such as a golf cart, for example, or may be portable and carried on a golf cart or a golf bag or by a person, such as a player, for example. A golf cart may be motor driven, engine driven or manually moved over the golf course. In addition to the fixed GPS receiver and the mobile GPS receiver, which may be stationary when used to practice the invention, the invention provides for a computer or data processor and may include one or more radios, to receive and/or send GPS Data received by GPS receivers, to computers, as discussed above. A read out means, for example, a monitor or screen, such as a cathode ray tube, a light emitting diode, screen, or liquid crystal screen, may be provided. The read out means may also be audible. A GPS Data converter means may be used, if desired, to convert or translate GPS Data into location coordinates such as latitude and longitude, for example, which define a location.
Preferably the mobile GPS receiver, the computer, the radio and the read out means are mounted on the golf cart, however, corresponding equipment may be transported by the player. The computer may receive GPS Data from a GPS receiver through a solid link, while also receiving other GPS Data from a second GPS receiver, through an air link, such as an RF receiver means, for example. The read out means may be a monitor, printer or other visual readout means, or may be an audible means.
GPS Data, received from satellites in the GPS system by a GPS receiver, is in radio frequency form and is translatable into angular distances or location coordinates, such as latitude and longitude, for example, which define a location on earth. The difference between two locations, each defined in latitude and longitude, is a latitude value and a longitude value which translate into a distance and direction of that distance. If two different locations, such as the locations of two spaced objects, for example, are defined by sets of latitude and longitude values, the difference between the latitude values of each set and the longitude values of each set is a latitude value and a longitude value which is translatable into a distance and an angle of that distance. If two sets of GPS Data define two locations accurately, with respect to the true locations, the difference between the definitions is the distance and direction between the actual locations. If the two sets of GPS Data define the locations inaccurately, with respect to the true locations, and the inaccuracy is common to each definition, the distance and direction is between two locations equally off-set from the two actual locations and therefore equal and corresponding to the distance and direction between the actual locations. Accurately defined locations are not required so long as the inaccuracy or off-set in the definition, from the true locations is common and corresponding to each set of two location definitions.
In practicing the invention using one or more GPS receivers in fixed locations, and one or more mobile GPS receivers, the GPS receiver in fixed location is preferably operated on a continuing basis, transmitting received GPS Data, relating to the site or location of the particular fixed GPS receiver. The mobile GPS receiver is operated in response to demand. The two sets of GPS Data used, one set of GPS Data defining one location and another set of GPS Data defining another, spaced location, are received coincidentally.
The two sets of GPS Data or the two sets of location coordinates translated from the two sets of GPS Data are mathematically combined, preferably by a computer or data processor programmed for the same. The latitude difference value and/or the longitude difference value may be converted into distance such as meters and centimeters or miles and yardage, for example, and compass direction Distance on a golf course, such as distance between the golf cart and the pin or distance between the golf ball on the fairway and the pin are preferably provided in yardage. Direction may be a magnetic direction or true direction.
In an operating system practicing the invention, it is preferred that a fixed GPS receiver receive GPS Data continuously and that the coupled radio transmit the GPS Data instantly and continuously. The mobile GPS receiver and the radio to which it is coupled operate on demand. A fixed GPS receiver and it associated equipment in a club or pro-shop on a golf course may be operated on a demand basis.